The present invention relates to an electric-discharge-machining power source for use in an electric discharge machine, and more particularly, to a transistor type electric-discharge-machining power source which is capable of increasing a machining speed.
In order to increase a machining speed in electric discharge machining, it is desirable to use machining pulses which are large in peak value but small in pulse width. Conventionally, a capacitor type electric-discharge-machining power source is employed so as to generate machining pulses which satisfy the aforementioned requirement. Recently, a transistor type electric-discharge-machining power source has been employed which has an electric current return circuit for protecting a transistor from a surge current (which is generated attributable to energy, accumulated in a stray inductance in a discharge circuit of the electric-discharge-machining power source) when the transistor is turned off.
However, it is difficult to generate machining pulses having a large peak value and a small pulse width in the transistor type electric-discharge-machining power source since restrictions are found in increasing a power source voltage and decreasing a stray inductance.